London Underground 1995 Stock
The London Underground's 1995 stock is used in daily service on the Northern Line. There are 106 six car trains in operation; they entered service between 12 June 1998 and 10 April 2001. The 1995 Stock shares many features with the 1996 Stock found on the Jubilee Line, and indeed both types were built by Alstom in Birmingham. The 1995 and 1996 Stock have different seating layouts and cab designs, and 1996 Stock trains are designed as seven-car trains. Despite the 1995 Stock designation, the step-plates found on the trains read '1996'. It is believed that the 1995 designation served solely to distinguish this stock from the similar stock on the Jubilee Line. Like the 1996 Stock, the trains were fitted with passenger operated door-open controls from new, but these are disabled. It is the only tube stock to use selective door opening. Examples of this can be found at and . The 1995 Stock is operated mainly with a dead man's handle at the driver's right hand. When the train is stopped the top of the handle is turned away from the position in which the driver holds it. To depart the driver turns the top of the handle and pushes the red lever forward. Traction control The 1995 stock and 1996 stock have similar bodyshells and were both built by Alstom. However, they use different AC traction control systems. The one on the 1995 stock is more modern than the 1996 stock, reflecting the fact that the latter's design spec was 'frozen' in 1991. The 1995 stock uses Alstom's "Onix" three-phase insulated-gate bipolar transistor (IGBT) drive. For comparison, the 1996 stock uses three-phase induction motors fed from a single-source inverter using a gate turn-off thyristor (GTO), derived from those on Class 465 Networker trains. Earlier London Underground stock, like most electric trains until the 1990s, used DC motors. These are now regarded as inefficient, partly because they are traditionally controlled by resistors, and partly because a three-phase AC induction motor is smaller and lighter for the same power. However, in an AC motor maximum torque can only be achieved when the resistance of the rotor windings equals the reactance. AC motors in an industrial setting tend to be operated more or less continuously and therefore large banks of resistors can be used on start-up to raise resistance and maintain torque. This would not be efficient in a small motor designed for stop/start operation. As a result, it was only the invention of electronic control systems from the 1980s onwards that made AC traction viable for trains. The motor can be supplied using an inverter, and by varying the inverter's output frequency it is possible to keep the frequency of the currents flowing in the rotor windings constant, and hence the reactance (while resistance remains fixed). The GTO used on the Jubilee line's 1996 stock achieves this by 'chopping' out short pulses of current, whereas modern AC traction such as the 1995 stock uses the IGBT (which is actually an amalgamation of a MOSFET and a conventional transistor), which can switch very high currents very rapidly without damage. In consequence, the 'whine' effect is less noticeable on 1995 stock than on 1996 stock. One disadvantage of IGBTs is that a higher voltage is dropped across them than other devices (high being about ¾ of a volt). As they conduct several thousand amperes, the resultant power dissipated by the IGBTs requires forced-air cooling. The cooling fans can be heard running and then shutting down depending on the amount of voltage being dissipated. Since October 2007, the 1995 stock has been fitted with the royal blue seat moquette which is also used on the 1996 and 1973 tube stock trains. The upgrade was completed in early 2008. Announcer System The Northern Line is fitted with an automated voice announcer (Celia Drummond). An example of the regular voice pattern is as follows: * "This station is . This train terminates at via ." * "This station is . Change here for Docklands Light Railway, Waterloo & City, Circle, Central and District Lines. This is a Northern Line train terminating at ." * "This station is . This is a Northern Line train (via Charing Cross) terminating at Kennington." * "This station is Highgate. This is a Northern Line train terminating at High Barnet." At some stations on the Northern Line such as Moorgate (Southbound) and Charing Cross, the platform is not long enough to accommodate all of the doors of the train, the 1995 stock is programmed to automatically cut out the first or last set of doors. At these stations, an announcement like this can be heard: * "The next station is . Upon arrival, the first set of doors will not open. Customers in the first carriage, please move towards the rear doors to leave the train. Please mind the gap between the train and the platform." Unlike other London Underground rolling stock, the 1995 Stock is unique in that at stations with interchanges to National Rail services, the announcer says "Main Line Suburban Rail Services" instead of "National Rail services": * "This station is . Change here for Bakerloo, Jubilee and Waterloo & City Lines, and Main Line Suburban Rail Services. This train terminates at . * "This station is . Change here for Main Line Suburban Rail Services. This train terminates at . * "This station is . Change here for Main Line Suburban Rail Services. This train terminates at Morden via ." The longest voice pattern can be heard at King's Cross St. Pancras and also at Euston: * "This station is . Change here for Circle and Hammersmith, Metropolitan, Piccadilly and Victoria Lines, and Main Line InterCity, Suburban, and International Rail services. This train terminates at ." * "This station is (Charing Cross Branch). Change here for southbound Northern Line services via from platform 6, Victoria Line and Main Line, Intercity and Surburban Rail services. This train terminates at via ." The corresponding announcement is: * "This station is (Bank Branch). Change here for southbound Northern Line services via from platform 2, Victoria Line and Main Line, Intercity and Surburban Rail services. This train terminates at via ." The shortest voice pattern can be heard at Oval: * "This station is . This train terminates at ." The voice pattern for closure of the next station is as follows: * "The next station is closed, this train will not be stopping at the next station." http://www.youtube.com/watch?v=8O-TuEBIjaw Video of clousure of next station on Northern line YouTube. Maintenance The Northern Line 1995 Tube stock trains are operated by Tube Lines / LUL, but are provided under a Service Provision contract through Northern Line Service Provision Ltd (NLSP), which is an Alstom venture. Maintenance is carried out by Alstom Transport Limited at Golders Green Traincare Centre in North West London situated behind station and at Morden Traincare Centre in South West London. There are also some "outbases" such as Edgware, and and station fitters based at and . Train details *Length per carriage 17.77 m *Width per carriage 2.63 m *Height 2.875 m *Total seating capacity per six-carriage train 200, plus 20 perch seats and 48 tip-up seats. There are also 24 wheelchair spaces. *Total passenger capacity per six-carriage train 914 References London Underground 1995 Stock entering in Leicester Square station External links * 1995 Tube Stock specifications (TfL) * 1995 Tube Stock - Squarewheels.org.uk 1995 de:London Underground 1995 Tube Stock hu:1995 típusú szerelvény (Londoni metró) ja:ロンドン地下鉄1995形電車 pt:Material circulante no Metropolitano de Londres 1995